Device for classifying persons or objects

ABSTRACT

A device for classifying persons or objects, in particular for occupant classification in a motor vehicle, includes an arrangement for acquiring characteristic data on the person to be classified or the object to the classified; at least one algorithm for extracting features from the instantaneously acquired characteristic data; at least one filter for determining the classification of the person or the object from the instantaneously extracted features, taking into account the time progression of the features extracted for the person to be classified or the object to be classified; and a first counter for initiating the resetting of the filter when the algorithm, during the first time interval specified by the first counter, has exclusively provided features for the non-presence of a person or an object, so that the resetting behavior of the algorithm, or the filter downstream from the algorithm, may be decoupled from the output of the determined classification in a simple manner. A holding member is connected downstream from the filter to forward the classification determined by the filter, and a second counter is provided to initiate the resetting of the holding member if the algorithm, even after the second time interval specified by the second counter has elapsed, has provided only features for the non-presence of a person or an object.

BACKGROUND INFORMATION

[0001] The present invention is directed to a device for classifying persons or objects, especially for occupant classification in a motor vehicle. This device includes means for acquiring characteristic data on the person to be classified or the object to be classified; at least one algorithm extracting features from the instantaneously acquired characteristic data; at least one filter determining the classification of the person or object from the instantaneously extracted features, the time progression of the extracted features for the person or object to be classified being taken into account; and a first counter, via which the resetting of the filter is initiated when the algorithm has provided exclusively features for the non-existence of a person or an object during the first time interval specified by the first counter.

[0002] The method according to the present invention may generally be used wherever persons or objects must be classified in some form or another. The classification may be implemented on the basis of widely varying criteria, such as size or weight of the person or object. Data of all kinds may be acquired as characteristic data as long as they allow conclusions with respect to the classification criteria. If, for example, a size classification is to be implemented, characteristic data on the person to be classified or the object to the classified may be acquired by video sensing, ultrasound sensing or even radar sensing.

[0003] The device according to the present invention is explained in greater detail in the following, by way of example, on the basis of a weight classification of vehicle occupants.

[0004] The triggering of restraint means in a motor vehicle usually occurs as a function of a variety of parameters, such as the seriousness of the collision and the position and the weight of the passengers. For that reason, not only the seat occupancy, but characteristic data for each individual occupant are detected as well, which allows conclusions as to the weight of the occupant, so that each occupant may be assigned a weight classification. In practice, force sensors, which are installed in the individual seats, are used to detect the characteristic data for such an occupant classification. The force sensors may be foil strain gauges for the direct measurement of weight. However, the force-sensor system may also be implemented in the form of a sensor mat having pressure-sensitive sensor cells, which are arranged in a matrix and may be activated individually, thus making it possible to detect the pressure distribution in the seat in the form of a value matrix. The heavier a person, the greater the depression of the seat material and the higher the number of activated sensor cells. Moreover, the pressure value per se detected by a sensor cell is, of course, dependent on the respective pressurization. In the evaluation of the pressure data acquired by the individual sensor cells of the sensor mat, the number of the activated sensor cells is, therefore, taken into account as well, in addition to the individual pressure values. A control device, which is likewise installed in the seat, carries out the evaluation. The result of the evaluation, namely the determined respective weight classification, is forwarded to the air bag control device, so that in the triggering of the restraint means the individual seat occupancy may be taken into account. This method is largely independent of external conditions, such as cold or wear.

[0005] In known standard devices for passenger classification, features are extracted from the continually detected pressure data with the aid of an appropriate algorithm, from which a filter, connected downstream from the algorithm, will then determine the weight classification. The filter parameters are continually updated and selected such that the progression over time of the earlier acquired and evaluated pressure data is also taken into account in the evaluation of the instantaneous pressure data or in the filtering of the features extracted therefrom. The weight classification of an occupant is newly determined every 0.7 s on the basis of the then current data. A resetting of the filter parameters is implemented if the algorithm recognizes that a seat is unoccupied for longer than 5 s. This reset is initiated by a simple counter, which specifies the time interval of approx. 5 s.

[0006] In the known device, the information “seat not occupied” is transmitted to the air bag control device with the resetting of the filter. As soon as the air bag control device receives the information “seat not occupied”, the restraint means for the respective seat are switched off, so that they are not triggered in a then occurring crash. Often, this has proven problematic, especially when a passenger gets up from his seat briefly, but for more than 5 s, without exiting the car, to remove a coat during the ride, for example. In such a case, the air bag control device receives the information “seat not occupied, the restraint means are switched off, and the respective occupant is unprotected, or insufficiently protected, until the air bag control device once again is provided with a realistic estimated value for the weight classification of the occupant.

SUMMARY OF THE INVENTION

[0007] The present invention proposes a device of the type mentioned in the introduction, by which the reset behavior of the algorithm, or the filter connected downstream from the algorithm, may be decoupled from the outputting of the determined classification in a simple manner.

[0008] According to the present invention, this is achieved by connecting, downstream from the filter, a holding member for the classification determined by the filter, and by providing a second counter via which the resetting of the holding member is initiated if the algorithm, even after the second time interval specified by the second counter has elapsed, only supplies features for the non-presence of a person or an object.

[0009] According to the present invention, the output of the determined classification is carried out via the holding member connected downstream from the filter. The holding function of the holding member is only relevant when the algorithm or the filter is reset because the non-presence of a person or an object has been detected. In this case, the holding member will continue to call up the most recently determined classification, until the holding member is reset as well or the algorithm once again provides features for a person or an object.

[0010] In an occupant classification that is to be taken into account in the triggering restraint means in a motor vehicle, it is possible by using the a fore-described holding member to account for the case that a passenger rises from his seat for only a brief time, without leaving the vehicle. Even if the filter is reset in such a case because the algorithm detects the non-occupancy of the respective seat, the last determined weight classification of the passenger may continue to be supplied to the air bag control. Only when a passenger change must be assumed, due to the duration of the non-occupancy, will the holding member be reset as well, so that only then the information “seat not occupied” will be supplied to the air bag control device.

[0011] The second counter provided according to the present invention, which initiates the resetting of the holding member, may be parameterized independently of the first counter, which initiates the resetting of the filter. In an advantageous variant of the device for occupant classification in a motor vehicle according to the present invention, the first counter initiates the resetting of the filter parameters if the algorithm has provided only features for the non-presence of a person or an object for at least 3 s. This ensures the reliable detection of a passenger change and the restarting of the classification. The second counter should only initiate the resetting of the holding member when the algorithm, for at least 20 s, has only provided features for the non-presence of a person or an object. Only then is it possible to reliably exclude that the respective occupant has risen from his seat only briefly, without changing the seat or leaving the vehicle.

BRIEF DESCRIPTION OF THE DRAWING

[0012] As was already discussed in detail above, there are various possibilities of advantageously embodying and further refining the teaching of the present invention. In this context, on the one hand, reference is made to the claims that are subordinate to claim 1 and, on the other hand, to the following description of an exemplary embodiment of the present invention in light of the drawing.

[0013] The single FIGURE shows a basic representation of a device for occupant classification in a motor vehicle according to the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0014] With the aid of the device shown in the single FIGURE, occupants of a motor vehicle are classified with respect to their weight. The individually determined weight classification is forwarded to an air bag control device (not shown here), so that this information may be taken into account in the triggering of restraint means. The device includes a pressure-sensor system in the form of a sensor mat (not shown here), installed in the respective seat, by which it is possible to continually detect the pressure distribution in the seat. The detected pressure distribution is supplied to an algorithm 1 of the device, which extracts features from the detected pressure distribution from which conclusions may be drawn as to the weight classification of the respective occupant. A filter 2 is connected downstream from algorithm 1, implementing a time averaging of the features extracted via the most recent pressure distribution, provided no passenger change has occurred. The filter parameters of filter 2, thus, are determined by the history of the extracted features.

[0015] When algorithm 1 provides the information “seat not occupied” for the first time, a first counter 3 is activated. This counter 3 sends a reset signal 4 to filter 2 and in this manner initiates the resetting of the filter parameters if algorithm 1 has provided exclusively the information “seat not occupied” during the time interval specified by counter 3—in this case, for 5 s.

[0016] According to the present invention, the weight classification determined from the detected pressure distribution with the aid of algorithm 1 and filter 2 is forwarded to the air bag control device via a holding member 5 connected downstream from filter 2. Holding member 5 continues to forward the most recently determined weight classification to the air bag control unit even if algorithm 1 has already provided the information “seat not occupied” and filter 2 is reset. A second counter 6 is provided for resetting holding member 5, which is likewise activated when algorithm 1 supplies the information “seat not occupied” for the first time. By transmitting a corresponding reset signal 1, counter 6 initiates the resetting of holding member 5 only if algorithm 1 has exclusively provided the information “seat not occupied” during the time interval—20 s in this case—specified by second counter 6. Only then may it be reliably assumed that a change in the seat occupation has occurred.

[0017] According to the present invention, first counter 3 and second counter 6 are able to be parameterized independently of one another. First counter 3 provides for a resetting of algorithm 1 or filter 2 when the respective seat is unoccupied, whereas second counter 6 continues to transmit to the air bag control device the most recently detected weight classification. The decoupling of algorithm 1 or filter 2 from the output ensures that algorithm 1 immediately resumes operation and implements a new classification once the seat is newly occupied. However, in the event that the seat is unoccupied for only a brief time, second counter 6 ensures that the occupant is nevertheless taken into account in the triggering of the restraint means, since the weight classification determined for him continues to be forwarded to the air bag control device. 

What is claimed is:
 1. A device for classifying persons or objects, in particular for occupant classification in a motor vehicle, comprising means for acquiring characteristic data on the person to be classified or the object to the classified; at least one algorithm (1) extracting features from the instantaneously acquired characteristic data; at least one filter (2) determining the classification of the person or the object from the instantaneously extracted features, taking into account the time progression of the features extracted for the person to be classified or the object to be classified; and a first counter (3) via which the resetting of the filter (2) is initiated when the algorithm, during the first time interval specified by the first counter (3), has provided exclusively features for the non-presence of a person or an object, wherein a holding member (5) for the classification determined by the filter (2) is connected downstream from the filter (2), and a second counter (6) is provided via which the resetting of the holding member (5) is initiated if the algorithm (1), even after the second time interval specified by the second counter (6) has elapsed, provides only features for the non-presence of a person or an object.
 2. The device as recited in claim 1, wherein the means for acquiring characteristic data on the person to be classified or the object to be classified include means for video sensing, ultrasound sensing or radar sensing.
 3. The device as recited in one of claims 1 or 2, wherein the means for acquiring characteristic data on the person to be classified or the object to be classified include foil strain gauges for determining the absolute weight, or a pressure-sensor system for determining the pressure distribution in the contact surface.
 4. The device as recited in claim 3, wherein the person or the object is classified with respect to its weight.
 5. The device for occupant classification in a motor vehicle as recited in one of claims 1 through 4, wherein the first counter (3) initiates the resetting of the filter (2) if the algorithm (1), for at least 3 s, has provided exclusively features for the non-presence of a person or an object.
 6. The device for occupant classification in a motor vehicle as recited in one of claims 1 through 5, wherein the second counter (6) initiates the resetting of the holding member (5) if the algorithm (1), for at least 20 s, has exclusively provided only features for the non-presence of a person or an object. 